Surge stabilizers are employed in the pumping art to control and reduce pressure surges and vibrations generated by the pumping action, in order to reduce or minimize destructive wear on parts of the pump and the piping network in which the pump is mounted. One such stabilizer is disclosed in Hugley U.S. Pat. No. 3,376,898 issued Apr. 9, 1968.
Typically, a surge stabilizer includes a cylindrical housing or case, and fittings for placing the interior of the case in pressure communication with the working fluid being pumped. Thus, whatever pressure surges occur in the working fluid will also occur in the case. Mounted within the stabilizer case is a cartridge or boot which is cylindrical in shape and has a flexible sidewall, together with relatively more rigid end caps, one of which is utilized to mount the cartridge in the case. Means are provided for pressurizing the interior of the cartridge with a gas, and it is normally so pressurized to a level selected with a view to the pressure conditions in the working fluid.
When a pressure surge occurs in the case, the energy involved is largely devoted to compressing the cartridge, and when a pressure rarefaction occurs, the energy stored as energy of compression in the cartridge is returned to the working fluid to restore its pressure. The net effect is to smooth out or dampen the pressure surges in the working fluid.
The manner in which the cartridge compresses within the case is of importance in the performance of the stabilizer, and in the wear life of the cartridge. When a pressure surge occurs, the cartridge is reduced in volume. It is preferred that the shrinkage occur as a shortening of the length of the cartridge, accompained and somewhat offset by an increase in its diameter substantially to the inside diameter of the case. However, in prior devices it has not always been possible to attain this mode of compression. Often the free floating end cap of the cartridge will "piston" or translate longitudinally into the boot. This hinders the smoothness of the operation and produces objectionably high wear in the flexible wall of the cartridge.